History lies around every corner of this Massachusetts city, which was founded in 1630. Boston is best explored on foot; follow the three-mile Freedom Trail for a sampling of its most notable landmarks. The marked trail leads to 16 historic sites such as the Old North Church, the Paul Revere House and Faneuil Hall. At the trail's end, you can visit the USS Constitution, also known as "Old Ironsides." It's the oldest commissioned warship in the U.S. Navy. Other options: Visit one of Boston's extraordinary museums; explore Cambridge, home to Harvard (it's just across the Charles River); or stop by the Bull & Finch Pub -- it inspired the TV show "Cheers."